FlashCopy interfaces
The setup of FlashCopy in a z Systems and Open System environments can be done by using various interfaces. This chapter provides a high level view of the interfaces available for FlashCopy. Details regarding command syntax for individual interfaces can be located in the appropriate book for the interface you are interested in using for FlashCopy management on the IBM System Storage DS8000.
This chapter include the following topics:
8.1 FlashCopy management interfaces: Overview
There are various interfaces available for the configuration and management of FlashCopy when used in a z Systems or an Open Systems environment with the DS8000. The following interfaces support both z Systems and Open Systems:
•DS CLI
You can download the DS CLI from the IBM website and then install it on a workstation. It communicates with the DS8000 Hardware Management Console (HMC).
For more information about the DS CLI command for FlashCopy, see IBBM DS8000 Series Command-Line Interface User’s Guide, SC27-8526.
•IBM Copy Services Manager
For more information about IBM Copy Services Manager, see Chapter 28, “IBM Copy Services Manager” on page 329.
For more information about the DS open API, see IBM System Storage DS Open Application Programming Interface Reference, GC35-0516.
•DS Open Application Programming Interface (DS Open API)
For more information about DS Open API, see IBM System Storage DS Open Application Programming Interface Reference, GC35-0516.
The following interfaces are specific to z Systems and can be used for FlashCopy management:
•TSO
For more information about TSO commands for FlashCopy see, z/OS DFSMS Advanced Copy Services, SC23-6847.
•ICKDSF
For more information about ICKDSF commands for FlashCopy, see ICKDSF User’s Guide, GC35-0033.
•DFSMSdss
For more information about DFSMSdss and FlashCopy usage, see DFSMSdss Storage Administration, SC23-6868.
•The ANTRQST API
For more information about the ANTRQST API usage for FlashCopy, see z/OS DFSMS Advanced Copy Services, SC23-6847.
•ANTTREXX API
For more information about the ANTTREXX API usage for FlashCopy see z/OS DFSMS Advanced Copy Services, SC23-6847
•Native z/VM command
For more information about z/VM native commands for FlashCopy, see CP Commands and Utilities Reference, SC24-6175.
•Native z/VSE IXFP SNAP command
For more information about native z/VSE commands for FlashCopy, see z/VSE V5R1.0 System Control Statements, SC34-2637.
•Native TPF commands (for z/TPF only)
8.2 FlashCopy command interface reference
Table 8-1 list the command interface reference for FlashCopy.
Table 8-1 FlashCopy command interface reference
|
Function
|
DFSMSdss Command
|
TSO Command
|
ANTTREXX Command or API1
|
ANTRQST API
|
ICKDSF Command
|
z/VM CP Command 2
|
DSCLI Command
|
|
FlashCopy
|
|||||||
|
FlashCopy Establish: full volume relationship
|
COPY FULL
|
FCESTABL
|
(ANTFREXX) FCESTABLISH
|
ILK=ESSRVCS REQUEST= FCESTABLISH
|
FLASHCPY ESTABLISH
|
FLASHCOPY ESTABLISH with cylinders 0-END specified
|
mkflash
|
|
FlashCopy Establish: data set
|
COPY DATASET
|
FCESTABL with extent ranges specified
|
-
|
ILK=ESSRVCS REQUEST= FCESTABLISH with extent ranges specified
|
-
|
FLASHCOPY ESTABLISH with cylinder ranges specified
|
-
|
|
FlashCopy Withdraw (Remove FlashCopy relationship)
|
DUMP with FCWITHDRAW parameter
|
FCWITHDR
|
-
|
ILK=ESSRVCS REQUEST= FCWITHDRAW
|
FLASHCPY WITHDRAW
|
FLASHCOPY WITHDRAW
|
rmflash
|
|
Non-persistent relationships are automatically removed as soon as background copy completes (all data copied to target)
|
-
|
||||||
|
FlashCopy Query (Display a current summary of FlashCopy activity for a device)
|
-
|
FCQUERY
|
FCQUERY3
|
ILK=ESSRVCS REQUEST= FCQUERY
|
FLASHCPY QUERY
|
QUERY FLASHCOPY Virtual FlashCopy
|
lsflash
|
|
FlashCopy Query (Display current detailed data for FlashCopy activity for a device
|
-
|
FCQUERY with SHOWRELS
|
FCQUERY
|
ILK=ESSRVCS REQUEST= FCQUERY
|
FLASHCPY QUERY RELATIONS
|
QUERY FLASHCOPY
|
lsflash -l
|
|
Relocate data set extents on a DASD volume.
|
DEFRAG
|
-
|
-
|
-
|
-
|
-
|
-
|
1 ANTTREXX is the REXX callable service; however, samples are also shipped with DFSMS in DGTCLIB so that they can be invoked similar to TSO commands. The sample programs are ANTFREXX for FlashCopy, ANTPREXX for Peer-to-Peer Remote Copy (PPRC), ANTRREXX for Global Mirror, and ANTXREXX for zGM, previously known as extended remote copy (XRC).
2 Native z/VM commands are listed; however, ICKDSF commands are also supported on z/VM.
3 Using the REXX samples provided, FCQUERY information is displayed in dump format.
8.3 FlashCopy control with the interfaces
Independently of the interface that is used, when you manage FlashCopy, the following basic sequence takes place:
1. FlashCopy is initiated through an interface.
The initialization process of a FlashCopy relationship is fast. At the end of this process, FlashCopy is established based on the parameters. All of the necessary meta structures are established. No data is physically copied yet.
2. FlashCopy runs in the background.
Any tracks physically copied from the source to the target volume are done in the background (background copy). Whether FlashCopy physically copies all of the tracks or only those tracks required to maintain the T0 copy is determined by keywords that are specified at initialization time.
3. FlashCopy completes.
FlashCopy relationships will either be automatically removed if all tracks are copied, or removed explicitly through a FlashCopy Withdraw command (persistent relationships must be explicitly withdrawn).
8.4 FlashCopy in z/OS using DFSMSdss
On z/OS, DFSMSdss and DFSMShsm provide some unique application solution support and some general default options with Flashcopy that can be modified to fit your environment. For instance, DFSMShsm calls DFSMSdss to perform data movement. So, the defaults set for DSS will reflect on HSM as well, unless overridden by the HSM parameters on invocation. FlashCopy if possible for volume copies and data set copies. Detailed information can be found in the following IBM publications:
•DFSMSdss Storage Administration, SC23-6868
•DFSMSdfp Storage Administration, SC23-6860
•DFSMShsm Storage Administration, SC23-6871
For the best performance during copy operations with DFSMSdss, specify the parameters in Table 8-2, as applicable to your task.
Table 8-2 Parameters that can improve the performance
|
DFSMSdss COPY command parameters
|
Performance improvements
|
|
ADMINISTRATOR
|
Allows a DFSMSdss authorized administrator to bypass access checking to data sets and catalogs.
|
|
ALLDATA(*)
|
Copies all allocated space (for organization types PS, PSU, PO, POU, or null).
|
|
ALLEXCP
|
Copies all allocated space (for organization types PS, PSU, PO, POU, or null), even if data sets are empty.
|
|
PURGE
|
Unexpired data sets on the target volume can be overlaid for a full or track copy operation.
|
FlashCopy is the preferred copy method for DFSMSdss. The FASTREPLICATION setting can be used to determine whether or not DS8000 FlashCopy should be used. See Table 8-3 for how this setting is used during DSS copy operations.
Table 8-3 Fast Replication Management for DFSMSdss
|
Parameter
|
Description
|
|
FASTREPLICATION(PREFERRED)
|
This value is the default. For DFSMSdss, DS8000 FlashCopy is the preferred method for data copy. If FlashCopy cannot be used, the CONCURRENT parameter ensures that concurrent copy is used. If CONCURRENT is not used or the concurrent copy function fails, traditional data copy methods are used.
|
|
FASTREPLICATION(REQUIRED)
|
For DFSMSdss, the DS8000 FlashCopy is the required method to copy the volume. If FlashCopy cannot be used, DFSMSdss fails the operation with error message ADR938E.
|
|
FASTREPLICATION(NONE)
|
DFSMSdss does not try to use the DS8000 FlashCopy.
|
|
Keyword usage: Do not use the FASTREPLICATION(NONE) parameter, as it prevents the usage of FlashCopy.
|
8.4.1 DFSMSdss Full volume FlashCopy
DFSMSdss can implicitly use the hardware function of the DS8000 to perform a full volume FlashCopy if the following conditions are met:
•The source and target volumes must have the same track format.
•The source volumes and target volumes are in the same DS8000.
•The source and target volumes must be online.
•The FASTREPLICATION(NONE) keyword must not be specified.
Not all tracks on the volume are copied when DFSMSdss starts FlashCopy for a full volume copy. DFSMSdss requests FlashCopy for allocated extents only.
To achieve balance between excluding free space and saving the number of FlashCopy relationships, up to 255 relations are created for each full volume copy. If there are more than 255 extents on the volume, extents are merged (to reduce the number of extents), resulting in some free space being copied.
8.4.2 DFSMSdss data set FlashCopy
DFSMSdss can implicitly use the hardware function of the DS8000 to perform a FlashCopy if the following conditions are met with the COPY DATASET command:
•The source and target types are the same.
•The source devices and target devices are in the same DS8000.
•The source and target volumes must be online.
The COPY DATASET command can be used with the parameters listed in Table 8-4.
Table 8-4 Parameters with COPY DATASET
|
Parameters with
COPY DATASET |
Performance improvements
|
|
NOPACKING
|
If COPY DATASET is used for a partitioned data set, the nopacking option specifies that the data set is not to be compressed during copy. This action allows DFSMSdss to start FlashCopy for the copy operation.
|
|
FCNOCOPY
|
If FlashCopy is used to perform the copy operation, do not perform a full background copy of the data.
|
|
ALLEXCP
|
Copy all allocated space (for organization types PS, PSU, PO, POU, or null), even if the data sets are empty.
|
|
PURGE
|
Unexpired data sets on the target volume can be overlaid for a full or track copy operation.
|
Depending on the type of data set, the DFSMSdss does not always start the FlashCopy hardware function to perform the copy. DFSMSdss Storage Administration, SC23-6868 provides detailed information regarding which functions are started by DFSMSdss depending on the type of data set.
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